I wouldn't advise anybody to store their seed in a cloud.
You definitely don't want to have it uploaded anywhere. Not even encrypted.
You never know who gains access to the files.
And you can never know whether there will be a vulnerability found in the software you used to encrypt the file.
This could easily lead to your mnemonic code / seed being exposed to the wrong person.
And you shouldn't trust encrypted archives either.
WinRAR, for example, implemented the encryption itself correctly, but used a 4 bit IV.
Any encrypted archive can be decrypted within a few minutes.
I don't know whether this has been fixed already, but such a huge mistake is just embarrassing.